The para-kayaker was an officer in the army when he trod on an Improvised Explosive Device in 2009 and his life changed completely. He lost both legs above the knee and broke his pelvis, but the changes went much deeper than that.

At 6ft 7in, and athletic and strong, he struggled to adjust to life with a disability.

"I always wanted to be viewed as someone who was capable of doing what he needed to do and just get on and do it and not be vulnerable."

Suddenly, though, he felt very vulnerable he says, an alien concept to him because of his job, his athleticism and his competence. He struggled for a long time, and acknowledging that he now needed to ask for help was the hardest bit.

He hadn't really processed these feelings before the London 2012 Paralympics, hadn't really "come to terms" with his disability and how it had impacted on his identity. But he found and enjoyed para-rowing and trained hard to make the games with rowing partner Samantha Scothern. Unfortunately they finished fourth, only a fraction of a second outside the medals.

Beighton says that London 2012 was a whirlwind and he realises now that he threw himself into sport to prevent him from dealing with his disability. It was a "protective approach", he says, "where I could focus on something I could control and manage rather than the stuff I couldn't."

After the games, and the difficult defeat, came a lot of soul-searching and coming to terms, truly, with his new reality.

He no longer lives in denial, waking up thinking he is in a bad dream, he says. Para-kayaking has been a big part of that. Now training and competing is as much about being happy with who he is and how he approaches life as it is about sport.

When Beighton goes out and competes in Rio, this internal growth won't be evident. The steely determination on his face won't reveal how much sport has been a part of his recovery, or how much he has grown over the last four years, mentally as much as physically.

But this time he might be smiling more, despite the result. He is determined to just enjoy the experience.

"There was a lot of pressure on London with the end result, the gold, to be able to justify the pressure of it, and the stress and effort that it took to get there," he says. "Rio's an opportunity for me to go and enjoy it and live in the moment and that's up there in terms of winning a medal for me."

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Media captionBeighton driven by Paralympic goal

When it comes to the practicalities, Beighton says Para-Kayak is a good sport because he doesn't have to wear his legs. It's "nice to be unencumbered, especially when it's hot and sweaty." Because he's an above-knee amputee his prosthetic sockets come right up to his groin and can be uncomfortable.

In the kayak he is in the KL2 classification, meaning he doesn't have any leg drive in the boat but does have full core and hip function so can lean forward in the boat.

In the gym he does a mixture of exercises with his legs on and off. There are perks of both - with his legs on it evens up his posture and balance because his stumps are different lengths and his pelvis is a "bit wonky", but he'll take his legs off for pull up competitions (to lose 8kg and give him an advantage) and also for "cool gymnastics stuff" like handstands.

He sees the kayak as a leveller - "it takes the legs out of the equation so I'm judged on a level with the rest of the guys. Why not just use the body as I've got it?"

Of course Beighton wants a medal, he's an athlete, but that one question sums up this year's games more so. He'll be using his body exactly as it is.